In the related art, there is a known laser-scanning microscope apparatus provided with a plurality of dichroic mirrors that can be placed in an optical path in a switchable manner (for example, see Patent Literature 1). With the microscope apparatus disclosed in Patent Literature 1, information about image displacements that occur when acquiring images is stored in advance for the individual dichroic mirrors, and, when one of the dichroic mirrors is selected, an X-Y scanner is controlled by means of a computer based on the image displacement information corresponding to the selected dichroic mirror, thus correcting displacements in acquired images caused by the individual dichroic mirrors due to thicknesses and inclinations thereof when placed in the optical path.